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Pocket Bicycles
Pocket Bicycles was the name of a manufacturer of portable bicycles located in Cambridge, Massachusetts in the 1970s. Design innovations While resembling many of the small-wheel folding bicycle designs of the time, the bicycle was distinctive in reducing the flexion of the down tube and hinge by use of cables kept under tension by the weight of the rider, saving weight and space compared to use of rigid tubing braces. Use of cables provided reduction of excessive vertical flex in the frame while still allowing easy adjustment of the degree of flexion retained, to act as a tunable suspension system absorbing much of the bumpiness of the ride normally associated with small wheel bicycles. See also * Bicycle frame * Guy (sailing) A guy (probably from Dutch ''gei'', " brail") is a line (rope) attached to and intended to control the end of a spar on a sailboat. On a modern sloop-rigged sailboat with a symmetric spinnaker, the spinnaker pole is the spar most commonly cont ... * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Portable Bicycle
A portable bicycle is a bicycle that has been designed to be small and light enough for easy carrying. It is usually dismantled to make a convenient bundle and the frame often has a folding action to facilitate this. The design of a portable bicycle involves a trade-off between ease of carrying and ease of riding. History The first popular bicycles were the large penny-farthings. The pioneering inventor, W. H. J. Grout of Stoke Newington, invented a portable version in which the large front wheel could be dismantled into four pieces so that they would fit into a carrying bag. In the 1890s, Captain Gérard of the 87th Regiment of French Infantry was an advocate of bicycles for military use. To enable his troops to operate in rough terrain, he devised a bicycle which could be folded in two and carried on the soldiers' backs; the weight was "between 22 and 26¼ lbs" (10–12 kg). The first time the Gérard portable bicycle was used, it "gave complete satisfaction and justifi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bicycle Suspension
Bicycle suspension is the system, or systems, used to ''suspend'' the rider and bicycle in order to insulate them from the roughness of the terrain. Bicycle suspension is used primarily on mountain bikes, but is also common on hybrid bicycles. Bicycle suspension can be implemented in a variety of ways, and any combination thereof: *Front suspension *Rear suspension *Suspension seatpost *Suspension saddle *Suspension stem (now uncommon) *Suspension hub Bicycles with only front suspension are referred to as hardtail and bicycles with suspension in both the front and rear are referred to as dual or full suspension bikes. When a bicycle has no suspension it is called rigid. Bicycles with only rear suspension are uncommon although the Brompton folding bicycle is equipped with rear only suspension. Although a stiffer frame is usually preferable, no material is infinitely stiff and therefore any frame will exhibit some flexing. Bicycle designers intentionally make frames in such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Footnotes
A note is a string of text placed at the bottom of a page in a book or document or at the end of a chapter, volume, or the whole text. The note can provide an author's comments on the main text or citations of a reference work in support of the text. Footnotes are notes at the foot of the page while endnotes are collected under a separate heading at the end of a chapter, volume, or entire work. Unlike footnotes, endnotes have the advantage of not affecting the layout of the main text, but may cause inconvenience to readers who have to move back and forth between the main text and the endnotes. In some editions of the Bible, notes are placed in a narrow column in the middle of each page between two columns of biblical text. Numbering and symbols In English, a footnote or endnote is normally flagged by a superscripted number immediately following that portion of the text the note references, each such footnote being numbered sequentially. Occasionally, a number between brack ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stays (nautical)
Stays are ropes, wires, or rods on sailing vessels that run fore-and-aft along the centerline from the masts to the hull, deck, bowsprit, or to other masts which serve to stabilize the masts. A stay is part of the standing rigging and is used to support the weight of a mast. It is a large strong rope extending from the upper end of each mast and running down towards the deck of the vessel in a midships and direction. The shrouds serve a similar function but extend on each side of the mast and provide support in the athwartships direction. The object of both is to prevent the masts from falling down but the stays also prevent springing, when the ship is pitching deep. Thus stays are fore and aft. Those led aft towards the vessel's stern are backstays while those that lead forward towards the bow are forestays. "To stay" is also a verb: to bring the ship's head up to the wind (to point the bow upwind). This is done in order to go about (to tack; tacking is sometime ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bracing (aeronautics)
In aeronautics, bracing comprises additional structural members which stiffen the functional airframe to give it rigidity and strength under load. Bracing may be applied both internally and externally, and may take the form of strut, which act in compression or tension as the need arises, and/or wires, which act only in tension. In general, bracing allows a stronger, lighter structure than one which is unbraced, but external bracing in particular adds drag which slows down the aircraft and raises considerably more design issues than internal bracing. Another disadvantage of bracing wires is that they require routine checking and adjustment, or rigging, even when located internally. During the early years of aviation, bracing was a universal feature of all forms of aeroplane, including the monoplanes and biplanes which were then equally common. Today, bracing in the form of lift struts is still used for some light commercial designs where a high wing and light weight are more impo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guy (sailing)
A guy (probably from Dutch ''gei'', "brail") is a line (rope) attached to and intended to control the end of a spar on a sailboat. On a modern sloop-rigged sailboat with a symmetric spinnaker, the spinnaker pole is the spar most commonly controlled by one or more guys. Types There are two primary types of guys used to control a spinnaker pole: *The afterguy, working guy, or simply guy and sometimes known as a brace is attached to the windward clew of the spinnaker, and runs through the jaws on the outboard end of the pole and back to the cockpit. The afterguy is used to rotate the outboard end of the pole around the mast in order to optimize the sail's effectiveness, depending on the direction of the wind. Because a spinnaker has two clews, there is always a second line identical to the afterguy attached to the leeward clew of the spinnaker. This is called the sheet and serves a slightly different function. When the boat jibes, the spinnaker pole will be moved from one si ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bicycle Frame
A bicycle frame is the main component of a bicycle, onto which wheels and other components are fitted. The modern and most common frame design for an upright bicycle is based on the safety bicycle, and consists of two triangles: a main triangle and a paired rear triangle. This is known as the ''diamond frame''. Frames are required to be strong, stiff and light, which they do by combining different materials and shapes. A frameset consists of the frame and fork of a bicycle and sometimes includes the headset and seat post. Frame builders will often produce the frame and fork together as a paired set. Variations Besides the ubiquitous diamond frame, many different frame types have been developed for the bicycle, several of which are still in common use today. Diamond In the diamond frame, the main "triangle" is not actually a triangle because it consists of four tubes: the head tube, top tube, down tube and seat tube. The rear triangle consists of the seat tube joined by p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Small Wheel Bicycle
Small may refer to: Science and technology * SMALL, an ALGOL-like programming language * Small (anatomy), the lumbar region of the back * ''Small'' (journal), a nano-science publication * <small>, an HTML element that defines smaller text Arts and entertainment Fictional characters * Small, in the British children's show Big & Small Other uses * Small, of little size * Small (surname) * "Small", a song from the album '' The Cosmos Rocks'' by Queen + Paul Rodgers See also * Smal (other) * List of people known as the Small The Small is an epithet applied to: *Bolko II the Small (c. 1312–1368), Duke of Świdnica, of Jawor and Lwówek, of Lusatia, over half of Brzeg and Oława, of Siewierz, and over half of Głogów and Ścinawa *Dionysius Exiguus (c. 470–c. 5 ... * Smalls (other) {{disambiguation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Performance Tuning
Performance tuning is the improvement of system performance. Typically in computer systems, the motivation for such activity is called a performance problem, which can be either real or anticipated. Most systems will respond to increased load with some degree of decreasing performance. A system's ability to accept higher load is called scalability, and modifying a system to handle a higher load is synonymous to performance tuning. Systematic tuning follows these steps: # Assess the problem and establish numeric values that categorize acceptable behavior. # Measure the performance of the system before modification. # Identify the part of the system that is critical for improving the performance. This is called the bottleneck. # Modify that part of the system to remove the bottleneck. # Measure the performance of the system after modification. # If the modification makes the performance better, adopt it. If the modification makes the performance worse, put it back the way it was. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambridge, Massachusetts
Cambridge ( ) is a city in Middlesex County, Massachusetts, United States. As part of the Boston metropolitan area, the cities population of the 2020 U.S. census was 118,403, making it the fourth most populous city in the state, behind Boston, Worcester, and Springfield. It is one of two de jure county seats of Middlesex County, although the county's executive government was abolished in 1997. Situated directly north of Boston, across the Charles River, it was named in honor of the University of Cambridge in England, once also an important center of the Puritan theology embraced by the town's founders. Harvard University, the Massachusetts Institute of Technology (MIT), Lesley University, and Hult International Business School are in Cambridge, as was Radcliffe College before it merged with Harvard. Kendall Square in Cambridge has been called "the most innovative square mile on the planet" owing to the high concentration of successful startups that have emerged in the vicinity ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tension (physics)
In physics, tension is described as the pulling force transmitted axially by the means of a string, a rope, chain, or similar object, or by each end of a rod, truss member, or similar three-dimensional object; tension might also be described as the action-reaction pair of forces acting at each end of said elements. Tension could be the opposite of compression (physics), compression. At the atomic level, when atoms or molecules are pulled apart from each other and gain potential energy with a restoring force still existing, the restoring force might create what is also called tension. Each end of a string or rod under such tension could pull on the object it is attached to, in order to restore the string/rod to its relaxed length. Tension (as a transmitted force, as an action-reaction pair of forces, or as a restoring force) is measured in newton (unit), newtons in the International System of Units (or pounds-force in Imperial units). The ends of a string or other object transmitt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guy-wire
A guy-wire, guy-line, guy-rope, or stay, also called simply a guy, is a tensioned cable designed to add stability to a free-standing structure. They are used commonly for ship masts, radio masts, wind turbines, utility poles, and tents. A thin vertical mast supported by guy wires is called a guyed mast. Structures that support antennas are frequently of a lattice construction and are called "towers". One end of the guy is attached to the structure, and the other is anchored to the ground at some distance from the mast or tower base. The tension in the diagonal guy-wire, combined with the compression and buckling strength of the structure, allows the structure to withstand lateral loads such as wind or the weight of cantilevered structures. They are installed radially, usually at equal angles about the structure, in trios and quads. As the tower leans a bit due to the wind force, the increased guy tension is resolved into a compression force in the tower or mast and a late ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
